That dire prediction comes in a new critique of the November ballot initiative written by Tien and UCLA Chancellor Charles Young, the departing leaders of UC's two showcase campuses. Their views pit them against Governor Pete Wilson and the regents who run the university -- and who voted last year to eliminate affirmative action on all nine campuses.

The chancellors will present their statement at a press conference orchestrated to show they are speaking on their own time: They are holding it off campus at a Pasadena hotel on a Sunday.

"The passage of Proposition 209 will unquestionably alter the quality of the educational experience provided by our respective campuses by radically reducing the extraordinary diversity that we have managed to achieve," the statement reads.

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Wilson spokesman Sean Walsh responded, "If citizen Young and citizen Tien wish to convey their personal beliefs, welcome to America. They are freely entitled to do so."

Proposition 209, also known as the California Civil Rights Initiative, would outlaw race and gender preferences in most public hiring, contracting and public education in the state. In the statement, Tien and Young say evidence that such a policy would drastically reduce the presence of minorities on their campuses compelled them to speak out.

Their decision to go public is significant because UC officials have been under pressure not to take a public stand on affirmative action since last year's vote.

"It doesn't take a brain surgeon to realize that if you went out on a big limb, you'd get fired over it," said one top UC official who requested anonymity. "It's a myth that you can truly speak out on your own behalf on something like this."

Already at odds with the regents over their high- profile opposition to last year's vote on affirmative action, both Tien and Young announced their resignations earlier this year. Although neither said openly that their differences with the regents were at the heart of their decision, experts widely viewed their departure as a symptom of a crisis in governance at the university resulting from the controversial vote.

Their resignations make them "bullet-proof," noted the UC official.

Because some university presidents have been criticized for using state resources to oppose CCRI, Tien and Young are using their own money to rent a room at the Ritz-Carlton in Pasadena for the announcement, according to a UC Berkeley official. Both will be in town for a meeting of university presidents. Those involved in the preparations have been making calls about the announcement from home or from pay telephones.

Until recently, when questioned about CCRI, Tien has said only that his position on affirmative action is well-known and that he is a "team player."

In an interview last month, he acknowledged that he has faced pressure from both sides in the debate.

"Sometimes you have to be very careful," he said. "People are watching you very carefully. I don't want to be singled out among the chancellors."

In fact, Tien and the Berkeley campus have been singled out by opponents of affirmative action, including Wilson and UC regent Ward Connerly, author of the regents' action resolution and chairman of the 209 campaign.

After Tien announced his resignation, Connerly accused him of being "sneaky" for implementing the Berkeley Pledge, a program to promote future diversity on the campus by offering academic help to underprivileged high school students.

And in an opinion piece published last month in the student-run Daily Californian, state Senator Bill Leonard, R-Upland, called Tien's support for affirmative action "a blundering effort to raise up more college-educated African Americans and Latinos."

Also last month, the presidents of the 23 California State University campuses took heat over reports that they planned to make a joint statement against CCRI. After Connerly accused them of campaigning on university time, the presidents decided to oppose 209 individually, not as a group.

The incident put other university chiefs on notice to proceed with caution. Later the same week, Tien said he felt an obligation to say something on 209, but was still weighing his options.

"If Berkeley doesn't keep our diversity," he said, "Berkeley will not be the same."

Subsequently, the campus released a report projecting that, without affirmative action, non-Asian minorities at Berkeley will drop from 23 percent of the freshman class to a maximum of 12.5 percent. Under the regents' policy, the first undergraduates to be admitted with the new rules will be those applying for spring 1998, but if Proposition 209 passes, it would take effect on November 6, the day after the election.

It was those realities that compelled the two chancellors to make a statement, said Read Scott-Martin, a spokesman for the No on 209 campaign. "This was definitely their idea," he said. "I don't think anybody gets these guys to move unless they're willing to move."